Austrian cross-country skier Johannes Duerr, "is already on his way home" after testing positive for EPO.

Johannes Duerr of Austria takes 3rd place during the FIS Cross-Country World Cup Tour de Ski Men's Final Climb on January 05, 2014 in Val di Fiemme, Italy.

Updated at 5:26 AM EDT on Sunday, Feb 23, 2014

Austrian cross-country skier Johannes Duerr was kicked out of the Sochi Games on Sunday after testing positive for the blood booster EPO. It is the fifth doping case - and most serious so far - at the Olympics.

"It is a black day for us," Austrian Olympic Committee President Karl Stoss said at a news conference on the final day of the games.

Duerr finished eighth in the men's skiathlon Feb. 9 and was tested seven days later in Austria, where he had flown back for training. He returned to Sochi and had been due to compete in the 50-kilometer mass start Sunday, the final cross-country event.

Stoss said the team was "shocked" by what happened, adding Duerr was tested 14 times before this season, all the results negative. He said the skier's accreditation was pulled and he was on his way home.

Best of the Sochi Olympics: Day 15

At the airport in Sochi, Duerr was remorseful. He told Austrian TV he can "only apologize to everyone."

"So many people have been doing all they could to help me and now I've disappointed them with my silliness," he said, adding he is not sure what awaits him.

None of the five athletes won medals in Sochi. The other four were: Latvian hockey player Vitalijs Pavlovs, Ukrainian cross-country skier Marina Lisogor, German biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani.

The Austrian cross-country and biathlon teams were at the center of a major doping scandal at the 2006 Turin Olympics. Italian police, acting on a tip, raided the team lodgings and seized blood doping equipment and other substances.

No Austrians tested positive at those games, but several were later banned for life by the International Olympic Committee. The IOC fined the Austrian Olympic Committee $1 million, and the Austrian ski federation cut funding for biathlon and cross-country for several years.

The 26-year-old Duerr has been the leading athlete in a new generation of cross-country skiers attempting to rebuild the sport's image in Austria. He debuted on the World Cup circuit in 2011 and finished third in this season's overall Tour de Ski standings.

"It's a great pity that after all successful participations of the Austrian team we have had this case of doping," Stoss said. "We will do everything that is needed of us to prevent this in future. But, of course, we can't say there will not be one."

The EPO test comes after an Olympics in which the Austrians won 17 medals going into the final day.

"This was really good work made by our team," Stoss said. "The athlete himself confessed that he is the only one who did that and he takes all the responsibility on himself."

The IOC is conducting 2,453 drug tests in Sochi, a record for the Winter Games. The Olympic body also stores doping samples for 10 years to allow for retesting when new methods become available.

There was only one positive test at the previous Winter Olympics four years ago in Vancouver. IOC President Thomas Bach said the beefed-up testing is working and catching violators.

"For me it was never a question of the numbers and how many," Bach said Saturday in an interview with The Associated Press on Saturday. "I think it shows we are on the right track."

Earlier, Pavlovs tested positive for the stimulant methylhexanamine following Latvia's loss to Canada in the quarterfinals Thursday.

Lisogor tested positive for trimetazidine on Tuesday after the women's team sprint. She said she had been taking medication for a thyroid condition but "forgot to declare" the drug on her doping form.

Sachenbacher-Stehle, a former two-time Olympic gold medalist, tested positive for methylhexanamine. She blamed a nutritional supplement and said she had never knowingly taken performance enhancers.

Frullani tested positive for dimetylpentylamine. The Italian Olympic Committee told the AP it believed Frullani, a former decathlete, bought the stimulant on the Internet from the United States since it is not available in Italy.